The objective of this research project is to elucidate the manner in which membrane structures are formed, in terms of the assembly of the membrane components, the proper integration of functional systems and the regulation of the synthesis of the various membrane components. A viral system has been developed that should greatly facilitate these investigations. We have developed a suppressor system for nonsense mutants of bacteriophage phi 6. This bacteriophage is unique in that it contains a genome of three pieces of double-stranded RNA and an envelope composed of protein and lipid. Temperature-sensitive and nonsense mutants of phi 6 have been isolated and they have been classified genetically and biochemically. A morphogenetic sequence will be established for the development of phi 6 by means of the analysis of particles made by nonsense mutants in nonsuppressor hosts and the kinetic analysis of the development of normal particles. The roles of the various membrane proteins of the virus in the formation of the envelope will be determined, as well as that of P12, a nonstructural protein involved in envelope formation. The role of lipid synthesis in the formation of the viral membrane will also be studied. Investigations of the structure of the virion will be carried out so as to complement the biogenesis experiments. Although the primary interest in this project is the elucidation of membrane formation, other areas of phi 6 development, such as the transcription and replication of the double-stranded RNA genome, that can be studied with unique facility in this system will also be investigated.